I must confess that I haven't checked who provided the core
partition-by (presumably Rich). But
whoever it was: he clearly knows what he's doing.
However there is still a bug spoiling the show a little bit.
The investigations lead us directly to the basic question of
partition-by should behave.
And what is elegance anyway? Of course this is a subjective topic. So I can only speak about my own sense of aesthetics. A recent thread on the clojure google group had some examples which touched me exactly there—at my aesthetic sense.